*
* Example with constructed data from p 280
*
open data ch10.dat
data(format=free,org=columns) 1 100 x y z1 z2 z3
*
* OLS (inconsistent because of correlation between x and residuals)
*
linreg y
# constant x
*
* The instruments are indicated using a separate "INSTRUMENTS" instruction. This
* list is used in later estimation instructions when you use the INST(RUMENTS)
* option. To switch instrument sets, use a new INSTRUMENTS instruction.
*
* Note that the instrument lists include CONSTANT. CONSTANT is a regressor itself
* (thus obviously correlated with the regressors), and is, by assumption,
* uncorrelated with the residuals (which are assumed to be mean zero).
*
instruments constant z1
linreg(inst) y
# constant x
*
instruments constant z2
linreg(inst) y
# constant x
*
instruments constant z3
linreg(inst) y
# constant x